Weather Calculators

What is Wind Chill?

Wind chill is the lowering of body temperature due to the passing-flow of lower-temperature air. Wind chill numbers are always lower than the air temperature for values where the formula is valid.

Formula:

Wind Chill = 35.74 + 0.6215T - 35.75V^0.16 + 0.4275TV^0.16

Where:

• T = Air Temperature (°F)
• V = Wind Speed (mph)
• Valid for temperatures ≤ 50°F and wind speeds ≥ 3 mph

What is Heat Index?

The heat index is a measure of how hot it really feels when relative humidity is factored in with the actual air temperature. The human body normally cools itself by perspiration, but when humidity is high, evaporation is reduced.

Key Factors:

• Air temperature
• Relative humidity
• Human body's ability to cool through perspiration
• Evaporation rate

Health Risks:

• Caution: Fatigue possible with prolonged exposure
• Extreme Caution: Heat stroke, heat cramps, or heat exhaustion possible
• Danger: Heat cramps and heat exhaustion likely
• Extreme Danger: Heat stroke highly likely

What is Dew Point?

The dew point is the temperature to which air must be cooled to become saturated with water vapor. When the air temperature equals the dew point, the relative humidity is 100%.

Comfort Levels:

• Below 60°F: Very comfortable, dry air
• 60-70°F: Comfortable for most people
• Above 70°F: Increasingly humid and uncomfortable
• Above 75°F: Very humid, oppressive

Agricultural Significance:

• Frost formation when dew point ≤ 32°F
• Crop stress when dew point > 70°F
• Disease risk increases with high dew points